Without limiting the scope of the invention, its background is described in connection with pharmaceutical agents that are delivered in an extended or sustained-release form, as an example.
One such method of making sustained release particles is taught in U.S. Pat. No. 6,120,787, issued to Gustafsson, et al, which teach a method of preparing parenterally administrable sustained release microparticles, that include preparing core particles in an aqueous medium that is essentially free from organic solvent, a biologically active substance being entrapped therein during or after said preparation, drying the core particles and coating the same with a release-controlling polymer by air suspension technique so as to create a shell on the core particles without any detrimental exposure of the active substance to organic solvent.
Another sustained-release composition includes an amorphous polymer are taught in U.S. Pat. No. 6,613,358, issued to Randolph, et al., which provided for a sustained release composition for sustained release of a pharmaceutical substance that includes a biocompatible polymer that is highly amorphous and a pharmaceutical substance in a hydrophobic ion complex with an amphiphilic material. A compressed antisolvent method for manufacturing the composition it taught as are various product forms incorporating the composition and various uses for the composition.
Yet another sustained release drug formulation is taught in U.S. Pat. No. 5,980,945, issued to Ruiz in which a sustained release drug formulation includes a drug; a biodegradable polymer that is insoluble in water; and an oil vehicle in which both the drug and the polymer are dissolved. The oil vehicle contains 10-100% by volume of a pharmaceutically acceptable oil and 0-90% by volume a pharmaceutically acceptable liquid carrier for the drug or the polymer.
Finally, U.S. Pat. No. 5,674,533 issued to Santus, et al., teaches pharmaceutical compositions for the controlled release of the anti-tussive, moguisteine, in a liquid suspension designed either as ready-to-use and time-stable liquid formulations with a shelf-life of at least two years, or as dry formulations that are reconstituted with water when needed and then remain stable throughout the treatment period. Santus teaches the use of coated microgranules for the controlled release of moguisteine having sizes ranging from 50 to 500 μm, preferably from 90 to 300 μm, which are capable of remaining easily in suspension in a liquid for extended times. The microgranules have moguisteine core, with one or more optional plasticizers and excipients, granulated into microgranules having sizes smaller than 500 μm, uniform surfaces, substantially spherical shapes, apparent densities of about 500 to 600 g/l and very low friabilities, made by wet-kneading micronised moguisteine using water or a mixture of water and other solvents. These initial microgranules are given controlled-release properties by, a first coating having essentially hydrophilic characteristics, which isolates the microgranules; a second coating having lipophilic characteristics on top of the first coating; and a third coating having hydrophilic characteristics.